Command or script to clean out library list?

Several months ago I upgraded both my motherboard and operating system (to Win7). I used Apple's recommendation on migrating all my iTunes files, and everything seemed to go well. I have a large music collection of more than a thousand files on my PC. I've set preferences in iTunes so that I manually manage everything; there is no auto syncing of any kind.

Although iTunes is of course installed on the C drive, all music files are in locations on a larger but internal D drive. About 600 of those song files in iTunes have a group name that allows me to select them and copy to my iPhone, which I listen to quite a lot.

Couple of weeks ago I logged into my PC and noticed the iTunes song list had duplicate entries for almost every song. At first I thought maybe the setting for copying music files to an iTunes library/folder on the C drive might have somehow gotten turned on. But no it was still off. I started doing "Get info" on dupes and sure enough they had all been copied to a new iTunes library and subfolder on the C drive. Don't really know or care how this could happen at this point. But I would like to know if there is a command or script I can run that will look through the iTunes song list, find each one with a path to the C drive iTunes folder, and delete that song entry. Tips?